Although their fertility is declining, they are still at risk of falling pregnant if they do not use contraception, according to research published in the Canadian Medical Association Journal.

However, the researchers said women aged over 40 tend to be less vigilant than younger women about contraception due to either the belief that there is a low risk of pregnancy or as a result of health concerns.

Rebecca H Allen, of Women & Infants’ Department of Obstetrics and Gynecology Division of Research, said: “The benefits of birth control outweigh the risk. Even for women with risk factors, there are methods that can be safely used.”

The researchers are aiming to educate patients and also help doctors find the most appropriate contraception for their patients who are over 40.

Dr Allen advises women over 40 to discuss their options with a doctor so that they can ascertain which type of contraception is best suited to their individual needs.

She says that forms of contraception they used when younger may not necessarily be the best option now, depending on their health status.

Women should continue to use contraception until they are assured that they have gone through the menopause, according to Dr Allen, which can be assumed when a woman of 50 or over has not had a menstrual cycle for a year.

It is also stated that contraception can offer the added benefit of easing perimenopausal symptoms.

Oestrogen-containing oral contraceptives or the progestin-releasing intrauterine device, for instance, can be used to help stem heavy menstrual bleeding that can take place in the perimenopause.

Oestrogen-containing contraceptives can also be used to help vasomotor symptoms such as hot flushes and night sweats, the researchers report, while one study suggested oestrogen-containing oral contraceptives might possibly prevent declines in bone density.

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